This invention pertains to a seal for a fertilizer injector of the type described in my previous U.S. Pat. No. 4,649,836, issued Mar. 17, 1987, and provides an improved seal and holder therefore, to distribute the fertilizer to the spoked injectors.
In my previous patent, I described a device adapted to inject fertilizer near the plant roots, thus providing for much more economical use of liquid fertilizer. This, as an incident of its use, also reduces the excess fertilizer on the ground which can later show up as a pollutant in ground water or surface water. Injecting the material, places it below the level at which surface water run-off will be affected. Also the use of the relatively smaller amounts, placed where the plant will use it, makes the fertilization just as effective while more apt to be fully absorbed by plant roots and thus, less likely to be leached into the ground water.
In that previous patent, I described a seal device between the stationary supply means for the fertilizer and the rotating disc carrying the injectors. This seal included principally a bushing formed of a plastic such as nylon across which the rotor plate slid as it rotated. The bushing was pressed against the plate by a resilient rubber-like washer which could be adjustably pressed by the bushing. While that method works reasonably well, I have discovered that the face of the bushing does sometimes become scored and scratched by irregularities on the face of the plate so that after a certain number of rotations, that scoring may result in sufficiently irregular wear as to cause leaks.
By my invention, I provide a simple means to rotate the bushing by small amounts as the rotor plate rotates so that the bushing is not always in the same position. Thus, scoring by repeated passage of the plate is reduced. Any wear is not continuous on the same part of the face of the bushing, but rather is spread so that the face wears more evenly. Also, by my invention, I reduce the need for adjustment of the bushing by providing that the pressure on the liquid fertilizer acts on the bushing to hold it against the rotor plate.